Vehicle positioning method and system based on laser device

ABSTRACT

The present application discloses a positioning method for a movable platform, including: detecting, by a laser positioning system (LPS) mounted on the movable platform, a plurality of reflectors mounted on a target object, wherein the movable platform is moving; calculating in real-time, by the LPS, according to the current position information, relative positions of the plurality of reflectors with respect to the LPS; and obtaining, by the LPS, a relative position of the movable platform with respect to the target object based on the relative positions of the plurality of reflectors with respect to the LPS. The present application also discloses positioning system that performs the positioning method.

RELATED APPLICATION

The present application is a continuation application of applicationSer. No. 16/876,388, which claims the benefit of priority to ChinesePatent Application No. CN201910436285.6, filed May 23, 2019, andentitled “Vehicle Positioning Method and System Based on Laser Device,”the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

This present disclosure generally relates to systems and methods forposition determination, and more particularly, to methods and systemsfor position determination for an autonomous vehicle.

BACKGROUND

With the development of autonomous driving technology, more and moreclosed or semi-open working environments, including the portenvironment, have begun to use the autonomous driving technology toassist and support the operation process of the closed or semi-openworking environments. A key advantage of the machine is its ability tocarry out 24 hours 7 days a week of uninterrupted work. Thus, forefficiency improvement and cost control, using unmanned container trucksto conduct port operations has become a future trend and an importantmeans of replacing the traditional port manual operation. During thisreplacement, vehicle positioning occupies an important position inunmanned vehicle operations.

At present, most vehicle positioning methods are to set sensors on theloading and unloading equipment to detect the position of the vehicleduring the container loading and unloading process, then extractinformation of the head, trailer and container part of the containertruck by extracting straight lines, rectangles, and then reversecalculate the location of the vehicle using the cloud server. However,this positioning method of remote feedback calculation cannot satisfythe precise positioning of the vehicle itself during the continuoustravel.

SUMMARY

According to an aspect of the present application, a positioning systemincludes a movable platform; a Lidar mounted on the movable platform todetect a plurality of reflectors mounted on a target object while themovable platform is moving, wherein each of the plurality of reflectorsincludes a reflective pillar; and at least one processor mounted on themovable platform and in communication with the Lidar and the movableplatform to: obtain in real-time, according to the current positioninformation, relative positions of the plurality of reflectors withrespect to the Lidar by: determining a plurality of cloud points for areflector, performing a coarse filtering on the plurality of cloudpoints to generate a coarse cloud point cluster, performing a finefiltering on the coarse cloud point cluster to generate a fine cloudpoint cluster, and determining the position of the reflector based onthe fine cloud point cluster, and obtain a relative position of themovable platform with respect to the target object based on the relativepositions of the plurality of reflectors with respect to the Lidar.

According to another aspect of the present application, a positioningmethod for a movable platform includes detecting, by a laser positioningsystem (LPS) mounted on the movable platform, a plurality of reflectorsmounted on a target object, wherein the movable platform is moving, andeach of the plurality of reflectors includes a reflective pillar;obtaining in real-time, by the LPS according to the current positioninformation, relative positions of the plurality of reflectors withrespect to the LPS by: determining a plurality of cloud points for areflector, performing a coarse filtering on the plurality of cloudpoints to generate a coarse cloud point cluster, performing a finefiltering on the coarse cloud point cluster to generate a fine cloudpoint cluster, and determining the position of the reflector based onthe fine cloud point cluster, and obtaining, by the LPS, a relativeposition of the movable platform with respect to the target object basedon the relative positions of the plurality of reflectors with respect tothe LPS.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. The foregoing and other aspects of embodiments of thepresent disclosure are made more evident in the following detaildescription, when reading in conjunction with the attached drawingfigures.

FIG. 1 is a schematic diagram illustrating an exemplary system formovable platform positioning according to some embodiments of thepresent disclosure;

FIG. 2 is a schematic diagram illustrating exemplary hardware and/orsoftware components of an exemplary computing device according to someembodiments of the present disclosure;

FIG. 3 is a schematic diagram illustrating exemplary hardware and/orsoftware components of an exemplary processing engine according to someembodiments of the present disclosure;

FIG. 4 is a block diagram illustrating another exemplary laserpositioning system according to some embodiments of the presentdisclosure;

FIG. 5A is a flowchart illustrating an exemplary process for positioningmethod for a movable platform according to some embodiments of thepresent disclosure;

FIG. 5B is a schematic diagram illustrating cloud point cluster of areflector before filtering; and

FIG. 5C is a schematic diagram illustrating cloud point cluster of areflector after filtering;

FIG. 6 is a flowchart illustrating an exemplary process for obtainingthe relative positions of the movable platform with respect to a targetobject according to some embodiments of the present disclosure; and

FIG. 7A-7D is a schematic diagram illustrating a reflector coordinateaccording to some embodiments of the present disclosure;

FIG. 8 is a flowchart illustrating an exemplary process for positioningmethod for a movable platform according to some embodiments of thepresent disclosure; and

FIG. 9 is a schematic diagram illustrating a reflector coordinateaccording to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the present disclosure and is provided in thecontext of a particular application and its requirements. Variousmodifications to the disclosed embodiments will be readily apparent tothose skilled in the art, and the general principles defined herein maybe applied to other embodiments and applications without departing fromthe spirit and scope of the present disclosure. Thus, the presentdisclosure is not limited to what the embodiments show, but is to beaccorded the widest scope consistent with the claims.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes,” and/or “including” when used in thisspecification, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

These and other features, and characteristics of the present disclosure,as well as the methods of operations and functions of the relatedelements of structure and the combination of parts and economies ofmanufacture, may become more apparent upon consideration of thefollowing description with reference to the accompanying drawing(s), allof which form a part of this specification. It is to be expresslyunderstood, however, that the drawing(s) is for the purpose ofillustration and description only and are not intended to limit thescope of the present disclosure. It is understood that the drawings arenot to scale.

The flowcharts used in the present disclosure illustrate operations thatsystems implement according to some embodiments of the presentdisclosure. It is to be expressly understood, the operations of theflowcharts may be implemented not in order. Conversely, the operationsmay be implemented in an inverted order or simultaneously. Moreover, oneor more other operations may be added to the flowcharts. One or moreoperations may be removed from the flowcharts.

FIG. 1 is a schematic diagram illustrating an exemplary system formovable platform positioning according to some embodiments of thepresent disclosure. The system 100 may include a laser positioningsystem (LPS) 111 mounted on a movable platform 110. The system 100 maybe implemented to use a plurality of reflectors (e.g., 121, 122, 123,124 or 125 as shown in FIG. 1 ) mounted on a target object 120 asreferences for positioning the movable platform 110. For example, thetarget object 120 may be an alignment target, i.e., a target that themovable platform 110 may align with. The movable platform 110 may beanything that is movable, and the target object 120 may be a referenceobject when the movable platform park. For example, when the movableplatform 110 is an autonomous navigating container truck in a port, thetarget object may be a crane to load a container to the truck. Asanother example, when the movable platform 110 is an autonomous cleaningrobot to vacuum a floor, the target object may be a dock for thecleaning robot to charge its battery.

The LPS 111 may include a Lidar 113 and a processing engine 112. Theprocessing engine 112 (e.g., detecting module 301) may detect theplurality of reflectors (e.g., 121, 122, 123, 124 or 125 as shown inFIG. 1 ) mounted on the target object 120. The Lidar 113 may emit one ormore laser beams 130 and scan the one or more laser beams 130 to theplurality of reflectors. The plurality of reflectors may reflect thelaser beam 130 to the LPS 111. The LPS (e.g., the processing engine 112or the detecting module 301 as shown in FIG. 3 ) may detect theplurality of reflectors via receiving laser reflections 132 (a.k.a., thereflected laser beam 132 of the laser beam 130) from the plurality ofreflectors.

A reflector (e.g., 121, 122, 123, 124 or 125 as shown in FIG. 1 ) may bea reflective pillar or a reflecting tag. The reflector may be made byreflecting materials. In some embodiments, the reflector may be a pillarwrapped by reflecting tapes or painted by reflecting paints, etc. Thereflector may be made in a certain shape. For example, the reflector maybe a column, a cube, a ball, a square sheet, a circular sheet, anirregular-shape sheet, or the like, or any combination thereof. Theprocessing engine 112 may receive the laser reflections 132 of areflector and generate a point cloud corresponding to the reflector.Accordingly, the point cloud may include information of the reflector.For example, the point cloud may reflect the shape of the reflector.Based on the point cloud, the processing engine 112 may determine theposition of the reflector. To this end, the processing engine 112 mayfirst determine shape-related parameters of the reflector, and then,based on the shape-related parameters, the processing engine 112 maydetermine a coordinate that mostly represents the location of thereflector. For example, if the reflector is a column or a pillar, theprocessing engine 112 may determine a plurality of parameters related toa center point, a centerline and/or a radius of the reflector, and thenuse the plurality of parameters to determine the coordinate of thepillar.

The plurality of reflectors may be arranged in a certain known orpredetermined pattern on the target object in order for the system 100to position. For example, the plurality of reflectors may be arranged ina row on the target object. A distance of two reflectors may be apredetermined value (e.g., 1 meter, 0.5 meter, 0.1 meter, etc.).

The target object 120 may include a reference point 180. The referencepoint 180 may be related to a geometric structure of the target object120. For example, the reference point 180 may be a geometric center ofthe target object 120. In some embodiments, the reference point 180 maybe related to a functional structure of the target object 120. Forexample, if the target object 120 may be a gantry crane (or a portalcane, etc.), then the reference point 180 may be related to a positionof the crane or a wheel of the gantry crane. The movable platform 110may include an alignment point 170. The alignment point 170 may berelated to a geometric structure of the movable platform 110. Forinstance, the movable platform 110 may be a vehicle, and the alignmentpoint 170 may be a geometric center of the movable platform 110 alongthe length of the movable platform 110. For another instance, themovable platform 110 may include a vehicle and a container carried ortowed by the vehicle, and the alignment point 170 may be a geometriccenter of the container in the length direction. The relative positionsof the movable platform with respect to the target object may beobtained by the LPS 111 may be considered as relative positions of thereference point of the movable platform with respect to the referencepoint of the target object.

After the relative positions of the movable platform 110 with respect tothe target object 120 are obtained by the LPS 111, the movable platform110 may move to align with the target object 120 based on the relativepositions of the movable platform with respect to the target object. Ata target position where the movable platform 110 is aligned with thetarget object 120, the reference point of the target object 120 and thealignment point on the movable platform 110 may form a certain patternby the alignment. For example, as shown in FIG. 1 , after the alignment,the reference point 180 of the target object 120 and the alignment point170 of the movable platform 110 may form a line 190. Line 190 may beperpendicular to the target object 120. If the target object 120 is thegantry crane and movable platform 110 includes a container, the cranemay lift the container from the movable platform 110.

FIG. 2 is a schematic diagram illustrating exemplary hardware and/orsoftware components of an exemplary computing device according to someembodiments of the present disclosure. The server 110, the terminal 130,and/or the database 140 may be implemented on the computing device 200according to some embodiments of the present disclosure. The particularsystem may use a functional block diagram to explain the hardwareplatform containing one or more user interfaces. The computer may be acomputer with general or specific functions. Both types of computers maybe configured to implement any particular system according to someembodiments of the present disclosure. The computing device 200 may beconfigured to implement any component that may perform one or morefunctions disclosed in the present disclosure. For example, thecomputing device 200 may be used to implement any component of thesystem 100 as described herein. Only one such computer device is shownpurely for convenience purposes. One of ordinary skill in the art wouldunderstand at the time of filing of this application that the computerfunctions relating to the service as described herein may be implementedin a distributed fashion on a number of similar platforms, to distributethe processing load.

The computing device 200, for example, may include COM ports 250connected to and from a network connected thereto to facilitate datacommunications. The computing device 200 may also include a processor(e.g., the processor 220), in the form of one or more processors (e.g.,logic circuits), for executing program instructions. For example, theprocessor 220 may include interface circuits and processing circuitstherein. The interface circuits may be configured to receive electronicsignals from a bus 210, wherein the electronic signals encode structureddata and/or instructions for the processing circuits to process. Theprocessing circuits may conduct logic calculations, and then determine aconclusion, a result, and/or an instruction encoded as electronicsignals. Then the interface circuits may send out the electronic signalsfrom the processing circuits via the bus 210.

The computing device 200 may further include program storage and datastorage of different forms including, for example, a disk 270, and aread-only memory (ROM) 230, or a random access memory (RAM) 240, forvarious data files to be processed and/or transmitted by the computingdevice. The exemplary computing device may also include programinstructions stored in the ROM 230, RAM 240, and/or other types ofnon-transitory storage medium to be executed by the processor 220. Themethods and/or processes of the present disclosure may be implemented asthe program instructions. The computing device 200 also includes an I/Ocomponent 260, supporting input/output between the computer and othercomponents. The computing device 200 may also receive programming anddata via network communications.

Merely for illustration, only one CPU and/or processor is illustrated inFIG. 2 . Multiple CPUs and/or processors are also contemplated; thus,operations and/or method steps performed by one CPU and/or processor asdescribed in the present disclosure may also be jointly or separatelyperformed by the multiple CPUs and/or processors. For example, if in thepresent disclosure the CPU and/or processor of the computing device 200executes both steps A and B, it should be understood that step A andstep B may also be performed by two different CPUs and/or processorsjointly or separately in the computing device 200 (e.g., the firstprocessor executes step A and the second processor executes step B orthe first and second processors jointly execute steps A and B).

FIG. 3 is a block diagram illustrating an exemplary processing engine112 according to some embodiments of the present disclosure. Theprocessing engine 112 may include a detecting module 301, a determiningmodule 302, a positioning module 303.

The detecting module 301 may determine a plurality of reflectors mountedon a target object that is detected by a laser positioning system (LPS)mounted on the movable platform. In some embodiments, the movableplatform may be moving.

As illustrated in FIG. 1 , the LPS 111 may include a Lidar 113 and aprocessing engine 112. The processing engine 112 (e.g., detecting module301) may detect the plurality of reflectors (e.g., 121, 122, 123, 124 or125 as shown in FIG. 1 ) mounted on a target object 120 mounted on themovable platform 110. The Lidar 113 may emit one or more laser beams andscan the one or more laser beams to the plurality of reflectors. Theplurality of reflectors may reflect the laser beams to the LPS 111. Thedetecting module 301 may detect the plurality of reflectors viareceiving these laser reflections from the plurality of reflectors.

The detecting module 301 may detect the plurality of reflectors (e.g.,121, 122, 123, 124 or 125 as shown in FIG. 1 ) mounted on the targetobject 120, which may be mounted on the movable platform 110. The Lidar113 may emit one or more laser beams and scan the one or more laserbeams to the plurality of reflectors. The plurality of reflectors mayreflect the laser beams to the LPS 111. The detecting module 301 maydetect the plurality of reflectors via receiving these laser reflections(i.e., the one or more laser beams reflected by the plurality ofreflectors) from the plurality of reflectors.

Then, the determining module 302 may obtain relative positions of theplurality of reflectors with respect to the LPS 111.

The determining module 302 may obtain relative positions of theplurality of reflectors with respect to the LPS 111 based on the laserreflections from the plurality of reflectors. The plurality ofreflectors may reflect the laser beam emitted by the Lidar to the LPS111. One or more characteristics of the laser reflections may be relatedto the relative positions of the plurality of the reflector with respectto the LPS 111. One or more characteristics of the laser reflections mayinclude the intensity of the reflection or an angle of the reflection.For instance, the intensities of laser reflections may be negativelyrelated to the distances from the reflector to the LPS 111. The Lidarmay emit a laser as a first signal, and the determining module 302 mayreceive the laser reflection as a second signal. By comparing theintensity of the first signal and the intensity of the second signal,the determining module 302 may determine a surface color/texture of thereflector. By comparing the time difference between the emitting of thefirst signal and receiving of the second signal, the determining module302 may determine a relative position of the reflector with respect tothe LPS 111.

The positioning module 303 may obtain relative positions of the movableplatform with respect to the target object. The plurality of reflectorsmay be mounted on the target object. The actual position of theplurality of reflectors on the target object is known. The position ofthe LPS 111 on the movable platform is also known. The positioningmodule 303 may obtain relative positions of the movable platform withrespect to the target object based on the relative positions of theplurality of reflectors with respect to the LPS 111, the position of theLPS 111 on the movable platform, and the position of the plurality ofreflectors on the target object.

It should be noted that the descriptions above in relation to theprocessing engine 112 are provided for the purposes of illustration, andnot intended to limit the scope of the present disclosure. For personshaving ordinary skills in the art, various variations and modificationsmay be conducted under the guidance of the present disclosure. However,those variations and modifications do not depart the scope of thepresent disclosure. For example, the processing engine 112 may furtherinclude a storage module (not shown in FIG. 3 ). The storage module maybe configured to store data generated during any process performed byany component of the processing engine 112. As another example, each ofthe components of the processing engine 112 may associate with a storagemodule. Additionally or alternatively, the components of the processingengine 112 may share a common storage module. Similar modificationsshould fall within the scope of the present disclosure.

FIG. 4 is a block diagram illustrating another exemplary LaserPositioning System (LPS) 111, according to some embodiments of thepresent disclosure. Other than the Lidar 113 (not shown in FIG. 4 ), theprocessing engine 112 may include an acquisition module 401, acalculating module 402, an establishing module 403, a configurationmodule 404, and a monitoring module 405.

The acquisition module 401 may be configured to operate a real-timedetection on the plurality of reflectors disposed on an alignment target(e.g., the target object 120 as shown in FIG. 1 ) to obtain currentposition information of each of the reflective pillars (e.g., theplurality of reflectors as shown in FIG. 1 ) relative to a laser deviceusing the laser device (e.g. the LPS 111 as shown in FIG. 1 ) preset onthe device to be aligned in real-time by the laser device installed onthe vehicle. The calculation module 402 may be configured to determinethe relative position of the vehicle with respect to the alignmenttarget (e.g., the target object 120 as shown in FIG. 1 ) according tocurrent position information, a preset coordinate system of thereflective pillar cluster, and the actual position information of eachof the reflective pillar.

The invention can quickly determine the vehicle position of the vehiclerelative to the alignment target (e.g., the target object 120 as shownin FIG. 1 ) according to the current position information in real-time,and satisfies the precise positioning of the vehicle itself during thecontinuous traveling of the vehicle.

Further, in some embodiments, the processing engine 112 may include theestablishing module 403.

The establishing module 403 may be configured to acquire positioninformation of each of the reflective pillars relative to the laserdevice and a motion state of the vehicle in real-time during themovement of the different postures of the vehicle, and establish analignment coordinate system based on the position information and themotion state, wherein the alignment coordinate system is a coordinatesystem on the vehicle for aligning the vehicle with the target object atthe target position.

Further, the establishing module 403 may further be configured tooperate the following: When the position information of at least tworeflective pillars relative to the laser device is obtained for thefirst time, the nearest reflective pillar from the laser device is takenas the origin of the coordinate system, and the other reflective pillarsare taken as the intersection points on the X-axis to establish thefirst pair of coordinate systems of the current vehicle runningposition. The X-axis coordinates of each reflecting column in thecurrent coordinate system are sorted and numbered. The establishingmodule 403 may establish a first alignment coordinate system of thecurrent vehicle position, and sort X-axis coordinates of each reflectivepillar in the current alignment coordinate system.

When the position information of the at least two reflective pillarsrelative to the laser device (e.g., the Lidar 113) is acquired again,the reflective pillar closest to the laser device is taken as the originof the coordinate system, and the other reflective pillars are used asthe intersection point on the X-axis to establish the second alignmentposition of the current vehicle running position. The establishingmodule 403 may use a neighbor algorithm to associate the secondalignment coordinate system with the first alignment coordinate systemaccording to the current vehicle motion state to obtain a thirdalignment coordinate system;

During the movement of the vehicle with different postures, theestablishment and association of the coordinate system are continuouslyperformed until a preset requirement is met to establish the alignmentcoordinate system.

Further, in some embodiments, the processing engine 112 may include asetting module 404. The setting module 404 may be configured to acquireparameter information of the laser device (e.g., the Lidar 113) beforeestablishing the alignment coordinate system, which is based on theposition information and the motion state of the setting module 404(i.e., the motion state of the vehicle or movable platform).

Further, in some embodiments, the processing engine 112 may furtherinclude a monitoring module 405;

The detection module 405 may be configured to detect the reflector aftersetting; Specifically, the reflectivity and distance characteristics ofeach reflective pillar are obtained, and the reflectivitycharacteristics are coarsely filtered according to the preset threshold.According to the distance feature, the reflectivity feature after coarsefiltration is filtered and the cluster points of each reflector areobtained by clustering. The cluster points of each reflective column arefitted with a cylinder respectively, and the parameters of the cylinderare retained.

In order to reduce noise interference, in some embodiments, theprocessing engine 112 may further include a filtering module. Thefiltering module may be configured to determine a Kalman filtering modelaccording to a vehicle after calculating a position of the vehiclerelative to the alignment target (e.g., the target object 120 as shownin FIG. 1 ). The vehicle position is filtered to obtain the filteredvehicle position.

It should be noted that the descriptions above in relation to the LPS111 or processing engine 112 are provided for the purposes ofillustration, and not intended to limit the scope of the presentdisclosure. For persons having ordinary skills in the art, variousvariations and modifications may be conducted under the guidance of thepresent disclosure. However, those variations and modifications do notdepart the scope of the present disclosure. For example, the processingengine 112 may further include a storage module (not shown in FIG. 4 ).The storage module may be configured to store data generated during anyprocess performed by any component of the processing engine 112. Asanother example, each of the components of the processing engine 112 mayassociate with a storage module. Additionally or alternatively, thecomponents of the processing engine 112 may share a common storagemodule. Similar modifications should fall within the scope of thepresent disclosure.

FIG. 5A is a flowchart illustrating an exemplary process for positioningmethod for a movable platform according to some embodiments of thepresent disclosure. The process 500 may be executed by the system 100.For example, the process 500 may be implemented as a set of instructions(e.g., an application) stored in a storage device (e.g., the ROM 230 orthe RAM 240) and invoked and/or executed by the processing engine 112(e.g., the processor 220 of the computing device 200 illustrated in FIG.2 and/or the modules and/or units illustrated in FIG. 3 ). Theprocessing engine 112 may execute the set of instructions and, whenexecuting the instructions, it may be configured to perform the process500. The operations of the illustrated process presented below areintended to be illustrative. In some embodiments, the process 500 may beaccomplished with one or more additional operations not described and/orwithout one or more of the operations discussed. Additionally, the orderin which the operations of the process as illustrated in FIG. 5A anddescribed below is not intended to be limiting.

In 502, a plurality of reflectors mounted on a target object may bedetected by the laser positioning system (LPS) 111 mounted on themovable platform 110. In some embodiments, the movable platform 110 maybe moving. For example, the movable platform may be a truck, a car, ahitch, a bus, a train, a subway, a vessel, an aircraft, an autonomousvehicle, or the like, or any combination thereof. For another instance,the movable platform 110 may include a vehicle and a container carriedor towed by the vehicle.

As illustrated in FIG. 1 , the LPS 111 may include a Lidar 113 and aprocessing engine 112. The processing engine 112 (e.g., the detectingmodule 301 or the acquisition module 401) may detect the plurality ofreflectors (e.g., 121, 122, 123, 124 or 125 as shown in FIG. 1 ) mountedon a target object 120 mounted on the movable platform 110. The Lidar113 may emit one or more laser beams and scan these to the plurality ofreflectors in real-time. The plurality of reflectors may reflect thelaser beam to the LPS 111. The LPS 111 (e.g., the processing engine 112or the detecting module 301) may detect the plurality of reflectors viareceiving these laser reflections from the plurality of reflectors.

A reflector may be a reflective pillar or a reflecting tag. Thereflector may be made in a certain shape. For example, the reflector maybe a column, a cube, a ball, a square piece, a circular piece, anirregular shape, or the like, or any combination thereof. The processingengine 112 may receive the laser reflections of a reflector and generatea point cloud related to the reflector. Thus, the point cloud may berelated to the shape of the reflector, and the plurality of reflectorsmay be arranged in a certain pattern on the target object. For example,the plurality of reflectors may be arranged in a row on the targetobject. Additionally, a distance of two reflectors may be apredetermined value (e.g., 1 meter, 0.5 meters, 0.1 meters, etc.).

The processing engine 112 may determine the shape-related parameters ofthe reflector. For example, if the reflector is a reflective pillar or areflective pillar, the processing engine 112 may determine a pluralityof parameters related to a center point, a centerline and a radius ofthe reflective pillar. The actual position and radius of the reflectivepillar may be predetermined. For example, the radius and height may bedetermined by the maximum applicable distance of the LPS 111 (e.g., alaser radar).

The reflective pillar may be mounted horizontally upward. For instance,the plurality of reflective pillars may be mounted vertically to ahorizontal plane, and geometric centers of the plurality of reflectivepillars can share the same horizontal plane. A center plane of thereflective pillar may be near the center plane position of the LPS 111,which means the center plane of the reflective pillar may be ahorizontal plan passing through the geometric center of the reflectivepillar. Furthermore, the center plane of the LPS 111 may be a horizontalplan passing through the geometric center of the LPS 111. A verticalheight of the center plane of the reflective pillar is substantially thesame as a vertical height of the center plane of the LPS 111. Thisconfiguration may provide a robust signal accuracy and for positioning.In some embodiments, the reflective pillar can be calibrated.Specifically, for n reflective pillars, the radius r₁, r₂, . . . , r_(n)and the distance d_(ij) between the center points of every 2 adjacentreflective pillars are measured, wherein i ∈ [1, 2, . . . , n], j ∈ [1,2, . . . , n]. In some embodiments, the reflective pillar may exist atleast three laser lines generate by the LPS 111 at a certain position. Alaser line (or a scanning line) may be a virtual or real line on thesurface of the reflective pillar including at least three reflectingpoints arranged in the same horizontal plane. Each of the reflectingpoints may represent a position on the surface of the reflective pillarwhere the reflective pillar reflects a laser beam emitted by the LPS 111from the certain position. The LPS 111 may determine the relativeposition information between LPS and the reflective pillar based on thelaser beams reflected to the LPS 111 corresponding to a laser line. Thusone reflective pillar may provide at least three pieces of relativeposition information between the LPS and the reflective pillar based onthe laser beams reflected to the LPS 111 corresponding to the at leastthree laser lines, by which the clustering process for the reflectivepillar after mentioned may be accurate.

In 504, relative positions of the plurality of reflectors with respectto the LPS 111 may be obtained by the LPS 111. The processing engine 112(e.g., the determining module 302 or the calculating module) may obtainrelative positions of the plurality of reflectors with respect to theLPS 111.

The processing engine 112 (e.g., the determining module 302 or thecalculating module 402) may obtain relative positions of the pluralityof reflectors with respect to the LPS 111 based on the laser reflections132 from the plurality of reflectors. The plurality of reflectors mayreflect the laser beam 130 emitted by the Lidar to the LPS 111. One ormore characteristics of the laser reflections 132 may be related to therelative positions of the plurality of the reflector with respect to theLPS 111. One or more characteristics of a laser reflection 132 mayinclude the intensity of the reflections or an angle of the reflection.For instance, the intensity of the laser reflection 132 may have anegative correlation with the distance from the reflector to the LPS111. The Lidar 113 may emit a laser beam 130 as a first signal, and theprocessing engine 112 may receive the laser reflection 132 as a secondsignal. By comparing the intensity of the first signal and the intensityof the second signal, the processing engine 112 may determine adifference of the intensities, thereby determining a relative positionof the reflector with respect to the LPS 111.

The Lidar 113 may emit and scan a laser beam to the reflector and theLPS 111 may receive a reflected laser beam (the reflection) and generatecloud points signals for the reflected laser beam based on thereflecting intensity of each cloud point. In some embodiments, theprocessing engine 112 may obtain a reflectivity feature and a distancefeature of each cloud point, and then perform coarse filtering on thereflectivity feature according to a preset threshold. In someembodiments, the coarse filtering satisfies the formula (1){P _(i)|intensity_(i) ≥Thr}  (1)wherein P_(i) denotes the ith cloud point. Intensity, denotes thereflecting rate of the ith could point. Thr denotes a preset threshold.The preset threshold may be K, and the value greater than or equal to Kmay be considered a reflector suspected area, and value less than kdirectly is directly filtered out.

The processing engine 112 may finely filter the coarse filteredreflectivity features according to their corresponding distancefeatures, and then cluster the cluster points of each reflective pillar.The finely filtering may be performed based on formula (2){P _(i) |Thr _(i)≤√{square root over (x _(i) ² +y _(i) ² +z _(i) ²)}≤Thr_(h)}  (2)wherein Thr_(i) denotes a minimum threshold, and Thr_(h) denotes amaximum threshold, x_(i) denotes X-axis coordinate of the ith cloudpoint, y_(i) denotes y-axis coordinate of the ith cloud point, and z_(i)denotes z-axis coordinate of the ith cloud point.

The processing engine 112 may ignore the z-axis data for clustering ofthe x-y plane point cloud, and only keep the cluster with the distanceless than d_(min) and the number of point clouds in the cluster betweenc_(min) and c_(max), where d represents distance; c_(min) represents theminimum number of points or point clouds in the cluster; and c_(min)represents the maximum points or point clouds in the cluster. Since thevolume of the reflective pillar is substantially unchangeable, the countof cloud points for one pillar may be in a certain range. Before theprocessing engine 112 may fine-filters the clustering as shown in FIG.5B, after fine-filtering clustering, as shown in FIG. 5C, the reflectorcan be stably detected.

The processing engine 112 may fit the cluster points of each of thereflective pillars into a cylinder and retains the parameters of thecylinder. The parameters of the cylinder may include a center point(c_(xi), c_(yi), c_(zi)), a cylinder center line vector (c_(vxi),c_(vyi), c_(vzi)), and a cylinder bottom radius c_(ri). Considering thepresence of noises in the laser point cloud, the processing engine 112may can also conduct a fit operation using a random consistent samplingalgorithm.

In 506, the LPS 111 may obtain relative positions of the movableplatform with respect to the target object. The processing engine 112(e.g., the positioning module 303 in FIG. 3 or the acquisition module401 and calculating module 402 in FIG. 4 ) may obtain relative positionsof the movable platform with respect to the target object. The pluralityof reflectors (i.e., the reflective pillars) may be mounted on thetarget object. The actual position of the plurality of reflectors on thetarget object is known. The position of the LPS 111 on the movableplatform is also known. The processing engine 112 (e.g., the positioningmodule 303 in FIG. 3 or the acquisition module 401 and calculatingmodule 402 in FIG. 4 ) may obtain the relative positions of the movableplatform with respect to the target object based on the relativepositions of the plurality of reflectors with respect to the LPS 111,the position of the LPS 111 on the movable platform, and the position ofthe plurality of reflectors on the target object.

For example, as shown in FIG. 1 , the target object 120 may include areference point 180. The reference point 180 may be related to ageometric structure of the target object 120. For example, the referencepoint 180 may be a geometric center of the target object 120. In someembodiments, the reference point 180 may be related to a functionalstructure of the target object 120. For example, the target object 120may be a gantry crane (or a portal cane, etc.), and the reference point180 may be related to a position of the crane of the gantry crane. Themovable platform 110 may include an alignment point 170. The alignmentpoint 170 may be related to a geometric structure of the alignment point170. For instance, the movable platform 110 may be a vehicle, and thealignment point 170 may be a geometric center of the movable platform110 in a length direction. For another instance, the movable platform110 may include a vehicle and a container carried or towed by thevehicle, and the alignment point 170 may be a geometric center of thecontainer in the length direction. The relative positions of the movableplatform 110 with respect to the target object 120 may be obtained bythe LPS 111, wherein the relative positions of the movable platform 110with respect to the target object 120 may be the relative positions ofthe alignment point 170 of the movable platform 110 with respect to thereference point 180 of the target object 120.

In 508, the processing engine 112 may direct the movable platform tomove to a target position according to the relative positions of themovable platform with respect to the target object 120. After therelative positions of the movable platform 110 with respect to thetarget object 120 are obtained by the LPS 111, the movable platform 110may move to align with the target object 120 based on the relativepositions of the movable platform 110 with respect to the target object120. To this end, while the movable platform is moving, the processingengine 112 may determine a comparison result by comparing a targetrelative position with the relative position of the movable platformwith respect to the target object, and then the processing engine 112may direct the movable platform to keep moving until the comparisonresult shows that the target relative position matches the relativeposition of the movable platform with respect to the target object.

At the target position where the movable platform 110 is finally alignedwith the target object 120, the reference point 180 of the target object120 and the alignment point 170 on the movable platform 110 may form acertain pattern or relationship. For example, as shown in FIG. 1 , afterthe alignment, the reference point 180 of the target object 120 and thealignment point 170 of the movable platform 110 may form a line 190perpendicular to the target object 120. Accordingly, if the targetobject 120 is the gantry crane and the movable platform 110 includes acontainer, and the movable platform 110 is parked at the targetposition, the crane may lift the container from the movable platform 110or may directly load a container to the movable platform 110.

The processing engine 112 may establish a reflector coordinate inreal-time based on the real-time positions of the plurality ofreflectors with respect to the LPS 111, and determine a change of thereflector coordinate in real-time with respect to the LPS 111, thenconvert the change of the reflector coordinate to the relative positionsof the movable platform with respect to the plurality of reflectors.Detailed description related to step 506 may be found elsewhere of thepresent disclosure (e.g., FIG. 6 and the description thereof.)

It should be noted that the above description of the process forconverting a floating-point value into a fixed-point value is providedfor the purpose of illustration, and not intended to limit the scope ofthe present disclosure. For persons having ordinary skills in the art,modules may be combined in various ways, or connected with other modulesas sub-systems. Various variations and modifications may be conductedunder the teaching of the present disclosure. However, those variationsand modifications may not depart from the spirit and scope of thisdisclosure.

FIG. 6 is a flowchart illustrating an exemplary process for obtainingthe relative positions of the movable platform with respect to thetarget object according to some embodiments of the present disclosure.The process 600 may be executed by the system 100. For example, theprocess 600 may be implemented as a set of instructions (e.g., anapplication) stored in a storage device (e.g., the ROM 230 or the RAM240), and invoked and/or executed by the processing engine 112 (e.g.,the processor 220 of the computing device 200 illustrated in FIG. 2and/or the modules and/or units illustrated in FIG. 3 and FIG. 4 ). Theprocessing engine 112 may execute the set of instructions and, whenexecuting the instructions, it may be configured to perform the process600. The operations of the illustrated process presented below areintended to be illustrative. In some embodiments, the process 600 may beaccomplished with one or more additional operations not described and/orwithout one or more of the operations discussed. Additionally, the orderin which the operations of the process as illustrated in FIG. 6 anddescribed below is not intended to be limiting.

In 602, the processing engine 112 (e.g., positioning module 303 in FIG.3 , or the acquisition module 401, establishing module 403 andcalculating module 402 in FIG. 4 ) may establish a reflector coordinatein real-time based on the real-time positions of the plurality ofreflectors with respect to the LPS 111. The reflector coordinate may beconfigured to position the movable platform. The reflector coordinatemay be related to positions of the plurality of reflectors. In someembodiments, the reflector coordinate may be related to the actualposition of the plurality of reflectors.

The reflector coordinate may be related to the relative position of theplurality of reflectors with respect the LPS 111. The processing engine112 may select a first reflector and a second reflector from theplurality of reflectors at the first moment. Then the processing engine112 may establish the reflector coordinate based on the relativepositions of the first reflector and the second reflector with respectto the LPS 111. The relative position of the first reflector is theorigin of the reflector coordinate of the current time, and X-axis ofthe reflector coordinate of the current time passes through the firstreflector and the second reflector. In some embodiments, the origin ofthe reflector coordinate of the current time may be the closestreflector to the LPS 111 of the current time.

FIG. 7A is a schematic diagram illustrating a reflector coordinate ofthe first moment. As shown in FIG. 7A, at the first moment, when themovable platform detects at least two reflectors (e.g., reflector 121and reflector 122), the processing engine 112 (e.g., positioning module303) may establish a coordinate 710 with respect to the first moment.The coordinate 710 of the first moment may include an origin which isthe relative position of the reflector 121. The X-axis of the reflectorcoordinates 710 of the current time passes through the first reflector(e.g., reflector 121) and the second reflector (e.g., reflector 122.)

After the movable platform moves for a certain time, the processingengine 112 may select a first reflector and a second reflector from theplurality of reflectors at a second moment. The first moment may beprior to and next to the second moment. Then the processing engine 112may establish the reflector coordinate based on the relative positionsof the first reflector and the second reflector with respect to the LPS111. The relative position of the first reflector is the origin of thereflector coordinate of the second moment, and X-axis of the reflectorcoordinate of the current time passes through the first reflector andthe second reflector. In some embodiments, the origin of the reflectorcoordinate of the second time may be the closest reflector to the LPS111 of the current time.

FIG. 7B is a schematic diagram illustrating a reflector coordinate ofthe second moment. As shown in FIG. 7B, at the second moment, when themovable platform detects at least two reflectors (e.g., reflector 122and reflector 123), the processing engine 112 (e.g., positioning module303 in FIG. 3 , or the acquisition module 401, establishing module 403and calculating module 402 in FIG. 4 ) may establish a coordinate 720with respect to the first moment. The coordinate 710 of the first momentmay include an origin which is the relative position of the reflector122. The X-axis of the reflector coordinates 720 of the second momentpasses through the first reflector (e.g., reflector 122) and the secondreflector (e.g., reflector 123.)

In 604, the processing engine 112 (e.g., positioning module 303, in FIG.3 or the acquisition module 401, establishing module 403 and calculatingmodule 402 in FIG. 4 ) may determine a change of the reflectorcoordinate in real-time with respect to the LPS 111. The processingengine 112 may determine the reflector coordinate in current time as afirst reflector coordinate, then obtain the reflector coordinate in amoment prior to the current time as a second reflector coordinate; andfinally determine the change by comparing the first reflector coordinateand the second reflector coordinate.

The processing engine 112 may compare a position or a direction of thereflector coordinate of the first moment with respect to the LPS 111 andthe reflector coordinate of the second moment with respect to the LPS111 to determine the position or the velocity of the movable platform.For example, as shown in FIG. 7 A and FIG. 7B, the processing engine 112(e.g., positioning module 303 in FIG. 3 , or the acquisition module 401,establishing module 403 and calculating module 402 in FIG. 4 ) maycompare a difference between the position information of reflector 121in the reflector coordinate of the first moment and the positioninformation of reflector 121 in the reflector coordinate of the secondmoment with respect to the LPS 111. For example, as shown in FIG. 7A andFIG. 7B, the processing engine 112 (e.g., positioning module 303 in FIG.3 , or the acquisition module 401, establishing module 403 andcalculating module 402 in FIG. 4 ) may compare a difference between adirection of the X-axis of the reflector coordinate of the first momentand the direction of the X-axis of the reflector coordinate of thesecond moment with respect to the LPS 111.

In 606, the processing engine 112 (e.g., positioning module 303 in FIG.3 , or the acquisition module 401, establishing module 403 andcalculating module 402 in FIG. 4 ) may convert the change of thereflector coordinate to the relative positions of the movable platformwith respect to the plurality of reflectors.

The processing engine 112 may compare a position or a direction of thereflector coordinate of the first moment and the reflector coordinate ofthe second moment to determine the position or the velocity of themovable platform. For example, as shown in FIG. 7 A and FIG. 7B, theprocessing engine 112 (e.g., positioning module 303 in FIG. 3 , or theacquisition module 401, establishing module 403 and calculating module402 in FIG. 4 ) may compare a difference between the positioninformation of reflector 121 in the reflector coordinate of the firstmoment and the position information of reflector 121 in the reflectorcoordinate of the second moment to determine the actual position orvelocity of the movable platform 110 with respect to a stationary pointon the ground. For example, as shown in FIG. 7A and FIG. 7B, theprocessing engine 112 (e.g., positioning module 303 in FIG. 3 , or theacquisition module 401, establishing module 403 and calculating module402 in FIG. 4 ) may compare a difference between a direction of theX-axis of the reflector coordinate of the first moment with respect tothe LPS 111 and the direction of the X-axis of the reflector coordinateof the second moment with respect to the LPS 111 to determine the actualposition or velocity of the movable platform 110. The processing engine112 may make the above determination by assuming that the motion of theX-axis is known. For example, the direction of the X-axis is in factstationary.

In some embodiments, the processing engine 112 (e.g., positioning module303 in FIG. 3 , or the acquisition module 401, establishing module 403and calculating module 402 in FIG. 4 ) may establish an LPS 111coordinate being a coordinate taking the Lidar 113 (e.g., the processingengine 112) as an origin. For example, as illustrated in FIG. 7C, theprocessing engine 112 may convert the reflector coordinate of the firstmoment 710 to the LPS 111 coordinate of the first moment 711. Theprocessing engine 112 may be the origin of the LPS 111 coordinate 711.For another example, as illustrated in FIG. 7D, the processing engine112 may convert the reflector coordinate of the first moment 720 to theLPS 111 coordinate of the second moment 721. The processing engine 112may be the origin of the LPS 111 coordinate 721. The processing engine112 (e.g., positioning module 303 in FIG. 3 , or the acquisition module401, establishing module 403 and calculating module 402 in FIG. 4 ) mayconverting the change between the LPS 111 coordinate of the first moment711 and the LPS 111 coordinate of the second moment 721 to the relativepositions of the movable platform with respect to the plurality ofreflectors.

It should be noted that the above description of the process forconverting a floating-point value into a fixed-point value is providedfor the purpose of illustration, and not intended to limit the scope ofthe present disclosure. For persons having ordinary skills in the art,modules may be combined in various ways, or connected with other modulesas sub-systems. Various variations and modifications may be conductedunder the teaching of the present disclosure. However, those variationsand modifications may not depart from the spirit and scope of thisdisclosure.

FIG. 8 is a flowchart illustrating an exemplary process for apositioning method for a movable platform according to some embodimentsof the present disclosure. The process 800 may be executed by the system100. For example, the process 800 may be implemented as a set ofinstructions (e.g., an application) stored in a storage device (e.g.,the ROM 230 or the RAM 240) and invoked and/or executed by theprocessing engine 112 (e.g., the processor 220 of the computing device200 illustrated in FIG. 2 and/or the modules and/or units illustrated inor FIG. 4 ). The processing engine 112 may execute the set ofinstructions and, when executing the instructions, it may be configuredto perform the process 500. The operations of the illustrated processpresented below are intended to be illustrative. In some embodiments,the process 500 may be accomplished with one or more additionaloperations not described and/or without one or more of the operationsdiscussed. Additionally, the order in which the operations of theprocess as illustrated in FIG. 8 and described below is not intended tobe limiting.

As illustrated in FIG. 8 , the exemplary process for the positioningmethod for a movable platform includes the following steps. In 801, thecurrent position information of each reflective pillar relative to thelaser device may be obtained via real-time detecting the plurality ofreflective pillars preset on the alignment target (e.g., the targetobject 120 as shown in FIG. 1 ) to be aligned in real-time by using alaser device (e.g., the LPS 111 as shown in FIG. 1 ) disposed on thevehicle (e.g., the vehicle 110 as shown in FIG. 1 ). In 802, the vehicleposition of the vehicle with respect to the alignment target (e.g., thetarget object 120 as shown in FIG. 1 ) may be obtained based on currentposition information, the alignment coordinate system of the presetreflective pillar cluster, and the actual position information of eachof the plurality of reflective pillars.

It should be noted that the laser device may be a laser radar, and itsmodel may be VLP-16. The laser device may be fixedly mounted on thevehicle, for example, by screws. In the motion of the vehicle, the laserdevice does not sway relative to the vehicle, and the accuracy of thefinal vehicle position determination may be improved. The reflectivepillar (e.g., one or more of the reflective pillars 121, 122, 123, 124,and 125 as shown in FIG. 1 ) may be made by winding a cylinder with amaterial having good reflective properties. The reflective pillar may bedisposed on the alignment target (e.g., the target object 120 as shownin FIG. 1 ). Several reflective pillars may be placed on the alignmenttarget. In some embodiments, the number of reflective pillars is greaterthan or equal to two. The alignment target is determined based on theactual application scenario and can be an inner-shore bridge of a port,a heap bridge, and a suspension bridge, etc. For example, in thescenario of a suspension bridge, the suspension bridge may be thealignment target. The reflective pillar is placed at a height of 1 to 6meters from the ground of the suspension bridge. The reflective pillarsare arranged on both sides of the suspension bridge, and the totalnumber is greater than or equal to two. This may be good for the controlof unmanned vehicles in a port environment, especially container trucks.

In the vehicle, the laser device may detect the relative position of thereflective pillars in real-time, that is, calculating the currentposition information of the reflective pillars with respect to the laserdevice (e.g., the Lidar 112 as shown in FIG. 1 ) based on the reflectionintensity of the reflective pillars. The real-time position of thevehicle may be determined in real-time according to the current positioninformation, the preset coordinate system of the reflective pillars andthe actual position information of each reflective pillar, as shown inFIG. 9 . For example, the actual position information of each of thereflective pillars may be obtained either before or after the reflectivepillar is actually set, which this application does not intend to limit.

In the vehicle, the laser device detects the relative position of thereflective pillar in real-time, that is, detects the current positioninformation of the reflective pillars relative to the laser deviceaccording to the reflection intensity of the reflective pillars. Thepresent disclosure can quickly determine the vehicle position of thevehicle relative to the target in real-time according to the currentposition information, and satisfy the vehicle itself during thecontinuous traveling process.

In some embodiments, the preset of the alignment coordinate system ofthe reflective pillar cluster may include the following steps.

During the movement of the different postures of the vehicle, the laserdevice acquires the position information of each of the reflectivepillars relative to the laser device and the motion state of the vehiclein real-time, and establishes a registration coordinate system based onthe position information and the motion state. Presetting the alignmentcoordinate system can speed up the positioning efficiency, and thealignment coordinate system based on the position information and themotion state can satisfy various vehicle movements and positions toaccurately locate the current vehicle.

In some embodiments, the motion of the different poses of the vehicle isa uniform linear motion of the vehicle.

The following is a detailed description of the establishment of thealignment coordinate system, which is the establishment of the alignmentcoordinate system based on the position information and the motionstate, including the following steps.

When the position information of at least two reflective pillarsrelative to the laser device is obtained for the first time, thereflective pillar closest to the laser device is taken as the origin ofthe coordinate system, and the other reflective pillar(s) of the atleast two pillars are used as other points on the X-axis to helpestablishing the first alignment coordinate of the current vehiclerunning position. Each of the reflective pillars in the X-axiscoordinate of the current alignment coordinate system is numbered. Inother words, the alignment coordinate system of the cluster isinitialized when the laser device detects at least two for the firsttime. The number may be in accordance with the respective positions ofeach pillar in the X-axis, from the one with a smaller X-axis coordinatevalue to the one with a larger X-axis coordinate value. For example, thenumber can be from id=0 to id=n from the origins of the X-axis.

When the position information of the at least two reflective pillarsrelative to the laser device is obtained again, the reflective pillarclosest to the laser device is taken as the origin of the coordinatesystem, and other reflective pillars of the at least two reflectivepillars are used as the other points on the X-axis to help establishingthe second alignment coordinate of the current vehicle running position.The Neighbor Algorithm is used to associate the second alignmentcoordinate system with the first alignment coordinate system accordingto the current vehicle motion state to obtain a third alignmentcoordinate system. The motion state of the vehicle may include thedirection of the motion, speed, and the like. The association betweenthe second alignment coordinate system and the first alignmentcoordinate system can be accomplished by means of the nearest neighbors.

During the movement of the vehicle under different poses, theestablishment and association of the coordinate system are continuouslyperformed until preset requirements are met to establish the alignmentcoordinate system so that the alignment coordinate system is able tocover every alignment relationship between the vehicle position and thereflective pillars.

In some embodiments, tracking can be performed during the motion of thevehicle using a Kalman tracking model. If the position information of atleast two reflective pillars relative to the laser device cannot beobtained at the same time within a single detection cycle during thecourse of vehicle motion, the reflective pillar information may bedetermined as unable be detected and obtained for the detection cycle,and only the motion model of the vehicle is used for status update; ifthe reflective pillars keep being undetectable non-detectable for apreset m detection cycles, it is considered that the reflective pillarscannot be detected, and record of the current reflective pillars isdeleted.

The actual position and radius of the reflector are required, and theradius and height are determined by the parameters of the selected laserdevice and the maximum applicable distance. In this embodiment, beforeestablishing the alignment coordinate system based on the locationinformation and the motion state, the following steps are furtherincluded.

The parameter information of the laser device may be obtained, and thereflective pillar on the alignment target (e.g., the target object 120as shown in FIG. 1 ) may be set according to the setting requirementsaccording to the parameter information. There are four criteria in thesetting requirements. The first one is that the reflective pillar shouldbe stable and will not shake after fixing. The second one is thehorizontal upward. The third one is that the center plane is near thecenter plane position of the laser device. The fourth point is that thenumber of reflective pillars is two or more. That is to say, at themaximum applicable distance, the laser device can obtain the currentposition information of at least three reflective pillars on thealignment target, and each reflective pillar contains 3 current positioninformation. The subsequent alignment coordinates can be improved. Thesystem determines the accuracy of the vehicle relative to the vehicleposition of the alignment target. In some embodiments, theretroreflective pillar can be calibrated. Specifically, the radius r₁,r₂, . . . , r_(n) of the n reflecting columns and the distance d_(ij)between the center points of the reflecting columns are measured.

Then, after the reflective pillar is set, it needs to be tested to seeif it meets the requirements. In some embodiments, specifically,obtaining a reflectivity feature and a distance feature of each of theretroreflective pillars, and performing coarse filtering on thereflectance characteristics according to a preset threshold; the coarsefiltering satisfies the following formula:{P _(i)|intensity_(i) ≥Thr}

P_(i) may denote the ith cloud point. Intensity, may denote thereflecting rate of the ith could point. Thr may denote a presetthreshold. The preset threshold may be K, and the value greater than orequal to K may be considered to be a reflector suspected area, and valueless than k directly is directly filtered out.

The coarse filtered reflectivity features may be filtered according tothe distance feature, and cluster the cluster points of each reflectivepillar. The finely filtering may be performed based on formula (2){P _(i) |Thr _(i)≤√{square root over (x _(i) ² +y _(i) ² +z _(i) ²)}≤Thr_(h)}  (2)

Thr₁ may denote a minimum threshold, and Thr_(h) may denote a maximumthreshold, x_(i) may denote X-axis coordinate of the ith cloud point,y_(i) may denote y-axis coordinate of the ith cloud point, and z_(i) maydenote z-axis coordinate of the ith cloud point.

The z-axis data for clustering of the XY plane point cloud may beignored, and only keep the cluster with the distance less than d_(min)and the number of point clouds in the cluster between c_(min) andc_(max). The clustering may be as shown in FIG. 5B before thefine-filtering, after fine-filtering clustering, as shown in FIG. 5C,the reflector can be detected very stably.

A cylindrical fit may be performed on the cluster points of each of thereflective pillars and retains the parameters of the cylinder. Theparameters of the cylinder may include a center point (c_(xi), c_(yi),c_(zi)), a cylinder center line vector (c_(vxi), c_(vyi), c_(vzi)), anda cylinder bottom radius cri. Considering the presence of laser pointcloud noise, A random consistent sampling algorithm may be used. Thevehicle position is filtered according to the preset Kalman trackingmodel of the vehicle to obtain the filtered vehicle position. In orderto avoid the influence of noise, the uniform linear motion is used asthe state update, and the detection of the reflective cluster is used asthe observation update, and the filtering result of the real-timeposition is outputted outward. The positioning accuracy of the vehicleis effectively improved, and the safety and stability of the automaticdriving in the port environment are enhanced.

It should be noted that the above description of the process fordetermining the directed graph is provided for the purpose ofillustration, and not intended to limit the scope of the presentdisclosure. For persons having ordinary skills in the art, modules maybe combined in various ways, or connected with other modules assub-systems. Various variations and modifications may be conducted underthe teaching of the present disclosure. However, those variations andmodifications may not depart from the spirit and scope of thisdisclosure.

Having thus described the basic concepts, it may be rather apparent tothose skilled in the art after reading this detailed disclosure that theforegoing detailed disclosure is intended to be presented by way ofexample only and is not limiting. Various alterations, improvements, andmodifications may occur and are intended to those skilled in the art,though not expressly stated herein. These alterations, improvements, andmodifications are intended to be suggested by this disclosure and arewithin the spirit and scope of the exemplary embodiments of thisdisclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics may be combined assuitable in one or more embodiments of the present disclosure.

Further, it will be appreciated by one skilled in the art, aspects ofthe present disclosure may be illustrated and described herein in any ofa number of patentable classes or context including any new and usefulprocess, machine, manufacture, or composition of matter, or any new anduseful improvement thereof. Accordingly, aspects of the presentdisclosure may be implemented entirely hardware, entirely software(including firmware, resident software, micro-code, etc.) or combiningsoftware and hardware implementation that may all generally be referredto herein as a “unit,” “module,” or “system.” Furthermore, aspects ofthe present disclosure may take the form of a computer program productembodied in one or more computer-readable media having computer-readableprogram code embodied thereon.

A computer-readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including electromagnetic, optical, or thelike, or any suitable combination thereof. A computer-readable signalmedium may be any computer-readable medium that is not acomputer-readable storage medium and that may communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device. Program code embodied on acomputer-readable signal medium may be transmitted using any appropriatemedium, including wireless, wireline, optical fiber cable, RF, or thelike, or any suitable combination of the foregoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object-oriented programming languagesuch as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB. NET,Python or the like, conventional procedural programming languages, suchas the “C” programming language, Visual Basic, Fortran 2003, Perl, COBOL2002, PHP, ABAP, dynamic programming languages such as Python, Ruby, andGroovy, or other programming languages. The program code may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (e.g., through the Internet using an Internet ServiceProvider) or in a cloud computing environment or offered as a servicesuch as a Software as a Service (SaaS).

Furthermore, the recited order of processing elements or sequences, orthe use of numbers, letters, or other designations, therefore, is notintended to limit the claimed processes and methods to any order exceptas may be specified in the claims. Although the above disclosurediscusses through various examples what is currently considered to be avariety of useful embodiments of the disclosure, it is to be understoodthat such detail is solely for that purpose and that the appended claimsare not limited to the disclosed embodiments, but, on the contrary, areintended to cover modifications and equivalent arrangements that arewithin the spirit and scope of the disclosed embodiments. For example,although the implementation of various components described above may beembodied in a hardware device, it may also be implemented as asoftware-only solution, e.g., an installation on an existing server ormobile device.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure aiding in theunderstanding of one or more of the various embodiments. This method ofdisclosure, however, is not to be interpreted as reflecting an intentionthat the claimed subject matter requires more features than areexpressly recited in each claim. Rather, claimed subject matter may liein less than all features of a single foregoing disclosed embodiment.

We claim:
 1. A positioning system, comprising: a movable platform; aLidar mounted on the movable platform to detect a plurality ofreflectors mounted on a target object while the movable platform ismoving, wherein each of the plurality of reflectors includes areflective pillar; and at least one processor mounted on the movableplatform and in communication with the Lidar and the movable platformto: obtain in real-time, according to the current position information,relative positions of the plurality of reflectors with respect to theLidar by: determining a plurality of cloud points for a reflector,performing a coarse filtering on the plurality of cloud points togenerate a coarse cloud point cluster, performing a fine filtering onthe coarse cloud point cluster to generate a fine cloud point cluster,and determining the position of the reflector based on the fine cloudpoint cluster, and obtain a relative position of the movable platformwith respect to the target object based on the relative positions of theplurality of reflectors with respect to the Lidar.
 2. The positioningsystem of claim 1, wherein the at least one processor further directsthe movable platform to move to a target position according to therelative positions of the movable platform with respect to the targetobject.
 3. The positioning system of claim 2, wherein to direct themovable platform to move to the target position the at least oneprocessor further: determines a comparison result by comparing a targetrelative position with the relative position of the movable platformwith respect to the target object; and directs the movable platform tokeep moving until the comparison result shows that the target relativeposition matches the relative position of the movable platform withrespect to the target object.
 4. The positioning system of claim 1,wherein to obtain the relative positions of the movable platform withrespect to the target object the at least one processor further:establishes a reflector coordinate in real-time based on the real-timepositions of the plurality of reflectors with respect to the Lidar;determines a change of the reflector coordinate in real-time withrespect to the Lidar; and converts the change of the reflectorcoordinate to the relative positions of the movable platform withrespect to the plurality of reflectors.
 5. The positioning system ofclaim 4, wherein to establish the reflector coordinate of a first momentthe at least one processor further: selects a first reflector and asecond reflector from the plurality of reflectors; and establishes thereflector coordinate based on the relative positions of the placing thefirst reflector and the second reflector with respect to the Lidar,wherein the relative position of the first reflector is the origin ofthe reflector coordinate of the current time, and an X-axis of thereflector coordinate of the current time passes through the firstreflector and the second reflector.
 6. The positioning system of claim5, wherein to establish the reflector coordinate of a second moment nextto the first moment the at least one processor further: selects thefirst reflector as an origin of the reflector coordinate of the secondmoment; and selects an axis that passes through the first reflector andthe second reflector as the X-axis of the reflector coordinate of thesecond moment time current.
 7. The positioning system of claim 4,wherein to determine the change of the reflector coordinate in real-timewith respect to the Lidar the at least one processor further: determinesthe reflector coordinate in a current time as a first reflectorcoordinate; obtains the reflector coordinate in a moment prior to thecurrent time as a second reflector coordinate; and determines the changeby comparing the first reflector coordinate and the second reflectorcoordinate.
 8. The positioning system of claim 4, wherein to convert thechange of the reflector coordinate to the relative positions of themovable platform with respect to the plurality of reflectors the atleast one processor further: establishes a Lidar coordinate being acoordinate taking a laser radar as an origin; and determines therelative change of positions of the Lidar with respect to thecorresponding reflector coordinate.
 9. The positioning system of claim1, wherein to obtain of the relative position of the movable platformthe at least one processor further: filters position of the movableplatform by a Kalman tracking model preset by the movable platform; andobtains a filtered position of the movable platform.
 10. The positioningsystem of claim 1, wherein the reflective pillar includes at least onelaser line including at least one reflecting point generated by theLidar, the at least one reflecting point represents a position of thereflective pillar, and the at least one processor determines therelative position between the movable platform and the reflective pillarbased on at least one laser beam reflected to the Lidar corresponding tothe at least one laser line.
 11. A positioning method for a movableplatform, comprising: detecting, by a laser positioning system (LPS)mounted on the movable platform, a plurality of reflectors mounted on atarget object, wherein the movable platform is moving, and each of theplurality of reflectors includes a reflective pillar; obtaining inreal-time, by the LPS according to the current position information,relative positions of the plurality of reflectors with respect to theLPS by: determining a plurality of cloud points for a reflector,performing a coarse filtering on the plurality of cloud points togenerate a coarse cloud point cluster, performing a fine filtering onthe coarse cloud point cluster to generate a fine cloud point cluster,and determining the position of the reflector based on the fine cloudpoint cluster, and obtaining, by the LPS, a relative position of themovable platform with respect to the target object based on the relativepositions of the plurality of reflectors with respect to the LPS. 12.The method of claim 11, further comprising: directing the movableplatform to move to a target position according to the relativepositions of the movable platform with respect to the target object. 13.The method of claim 12, wherein the directing of the movable platform tomove to the target position includes: determining a comparison result bycomparing a target relative position with the relative position of themovable platform with respect to the target object; and keep moving themovable platform until the comparison result shows that the targetrelative position matches the relative position of the movable platformwith respect to the target object.
 14. The method of claim 11, whereinthe obtaining of the relative positions of the movable platform withrespect to the target object includes: establishing a reflectorcoordinate in real-time based on the real-time positions of theplurality of reflectors with respect to the LPS; determining a change ofthe reflector coordinate in real-time with respect to the LPS; andconverting the change of the reflector coordinate to the relativepositions of the movable platform with respect to the plurality ofreflectors.
 15. The method of claim 14, wherein establishing of thereflector coordinate of a first moment includes: selecting a firstreflector and a second reflector from the plurality of reflectors; andestablishing the reflector coordinate based on the relative positions ofthe placing the first reflector and the second reflector with respect tothe LPS, wherein the relative position of the first reflector is theorigin of the reflector coordinate of the current time, and an X-axis ofthe reflector coordinate of the current time passes through the firstreflector and the second reflector.
 16. The method of claim 15, whereinthe establishing of the reflector coordinate of a second moment next tothe first moment includes: selecting the first reflector as an origin ofthe reflector coordinate of the second moment; and selecting an axisthat passes through the first reflector and the second reflector as theX-axis of the reflector coordinate of the second moment time current.17. The method of claim 14, wherein the determining of the change of thereflector coordinate in real-time with respect to the LPS includes:determining the reflector coordinate in a current time as a firstreflector coordinate; obtaining the reflector coordinate in a momentprior to the current time as a second reflector coordinate; anddetermining the change by comparing the first reflector coordinate andthe second reflector coordinate.
 18. The method of claim 14, wherein theconverting of the change of the reflector coordinate to the relativepositions of the movable platform with respect to the plurality ofreflectors includes: establishing an LPS coordinate being a coordinatetaking a laser radar as an origin; and determining the relative changeof positions of the LPS with respect to the corresponding reflectorcoordinate.
 19. The method of claim 11, wherein the calculating of therelative position of the movable platform includes: filtering positionof the movable platform by a Kalman tracking model preset by the movableplatform; and obtaining a filtered position of the movable platform. 20.The method of 11, wherein the reflective pillar includes at least onelaser line including at least one reflecting point generated by the LPS,the at least one reflecting point represents a position of thereflective pillar, and the method further comprising: determining therelative position between the movable platform and the reflective pillarbased on at least one laser beam reflected to the LPS corresponding tothe at least one laser line.